1. Field of the Invention
The present invention relates to a method and an apparatus for assisting the hearing of persons with hearing impairment or advanced age.
2. Description of the Background Art
In general, when the hearing ability such as a critical speed for speech recognition (a maximum speech speed for which the speech can be recognized correctly) is lowered due to the hearing impairment or the advanced age, the rate of correct speech recognition for the speeches uttered at normal speech speed or faster than normal speech speed considerably decreases.
Conventionally, a hearing aid device has been the only means for providing an assistance to such a person with handicapped hearing ability. However, the conventional hearing aid device functions only to compensate the transmission characteristics of the external ear and the middle ear in the auditory sense system by means of simple frequency characteristic improvement and gain control, so that it has been impossible for a conventional hearing aid device to compensate the lowering of the speech recognition ability related to the deterioration of the central auditory sense system.
In this respect, it is possible to make it easier for those who have the handicapped hearing ability to hear the speech correctly, by lowering the speech speed uniformly while maintaining the other speech characteristics.
However, when the speech speed is lowered uniformly, the speech utterance period is inevitably extended, and such an extended speech utterance period can cause the serious problem in a case of broadcasting or tape recording in which the period of time available for the utterance of the speech is limited in advance.
In addition, such a slowed down speech utterance can cause the further serious problem in a case of the TV broadcasting in which the speech is delivered in correspondence to the displayed visual information, such that the discrepancy between the slowed down speech utterance and the normal speed visual information may cause the confusion which rather obstructs the hearing.